ReprojectGLT Task

This task reprojects a raster georeferenced by a GLT (Geographic Lookup Table) to standard map information.

Example

This example georeferences and removes bowtie artifacts from an NPP VIIRS Land Surface Temperature EDR image.

; Start the application

e = ENVI()

; Open an NPP VIIRS unprojected raster

VIIRSFile = 'GMTCO-VLSTO_npp_d20150226_t0452277_e0458081_b17263_c20150327102544074141_noaa_ops.h5'

Raster = e.OpenRaster(VIIRSFile)

; Raster[0] is the LST raster

; Raster[1] is the Latitude raster

; Raster[2] is the Longitude raster

; Raster[3] is the Height raster

; Raster[4] is the Quality raster

; Get the reprojection task from the catalog of ENVITasks

Task = ENVITask('ReprojectGLT')

; Define inputs

Task.Input_Raster = Raster[0]

Task.Latitude_Raster = Raster[1]

Task.Longitude_Raster = Raster[2]

Task.Quality_Raster = Raster[4]

Task.Quality_Flag = 255

; Run the task

Task.Execute

; Get the collection of data objects currently available in the Data Manager

DataColl = e.Data

; Add the output to the Data Manager

DataColl.Add, Task.OUTPUT_RASTER

; Display the result

View = e.GetView()

Layer = View.CreateLayer(Task.OUTPUT_RASTER)

Syntax

Result = ENVITask('ReprojectGLT')

Input parameters (Set, Get): INPUT_RASTER, LATITUDE_RASTER, LONGITUDE_RASTER, QUALITY_RASTER, INTERPOLATION_METHOD, POLAR, QUALITY_FLAG, OUTPUT_RASTER_URI

Output parameters (Get only): OUTPUT_RASTER

Parameters marked as "Set" are those that you can set to specific values. You can also retrieve their current values any time. Parameters marked as "Get" are those whose values you can retrieve but not set.

Input Parameters

INPUT_RASTER (required)

Specify the raster to reproject.

INTERPOLATION_METHOD (optional)

The GLT algorithm establishes a regular output grid and finds the best location for each source image pixel. Any output grid point for which a source pixel could not be found will be filled using the nearest valid neighbor or with a distance-weighted average of the surrounding valid values.

The default interpolation method for reprojection is a distance-weighted average, which creates an image with the fewest visible interpolation artifacts.

Set the INTERPOLATION_METHOD parameter to 1 to perform nearest-neighbor interpolation in cases where the set of valid pixel values should not be modified (for example, when values represent the integral values of a classification).

LATITUDE_RASTER (optional)

Optionally specify a raster that represents the Latitude band of a GLT image. If not set, the Latitude band from the INPUT_RASTER is used (the INPUT_RASTER must have GLT projection).

LONGITUDE_RASTER (optional)

Optionally specify a raster that represents the Longitude band of a GLT image. If not set, the Longitude band from the INPUT_RASTER is used (the INPUT_RASTER must have GLT projection).

OUTPUT_RASTER_URI (optional)

Specify a string with the fully qualified filename and path of the associated OUTPUT_RASTER.

If you do not specify this parameter, or set it to an exclamation symbol (!), ENVI creates a temporary file.
If you set it to the hash symbol (#), ENVI creates a file in the temporary directory, but this file will not be deleted when ENVI closes.

POLAR (optional)

The default output projection is Geographic WGS-84. Set this parameter to true for a Polar Stereographic WGS-84 projection if the imagery covers the polar regions.

QUALITY_FLAG (optional)

Specify a value to set on the Quality Flag raster (specified by the QUALITY_RASTER parameter). The default value is 2, which is used to reproject some NPP VIIRS products. For EDR-Derived NPP VIIRS products and MODIS products, set this parameter to 255.

QUALITY_RASTER (required)

Specify a raster that represents the Quality Flag band of a GLT image.

Output Parameters

OUTPUT_RASTER

This is a reference to the output raster of filetype ENVI.

Methods

Execute

Parameter

ParameterNames

Properties

Version History

ENVI 5.1	Introduced
ENVI 5.2	The POLAR parameter is a Boolean type; valid options are true or false.
ENVI 6.0	Removed LATITUDE_RASTER and LONGITUDE_RASTER parameters.
ENVI 6.1	Re-added LATITUDE_RASTER and LONGITUDE_RASTER as optional parameters.